Why Cultural Evolution Is Real (And What It Is)

Cultural evolution represents an entire field of study. It has the potential, like biological evolution, to be a mechanism underlying and connecting many fields of study. This short introduction will pull together a few themes and compelling stories from this large field and present some of its concepts, mechanisms, and evidence—hopefully enough to increase the reader’s suspicion of the claim that cultural evolution is a “myth.”

John Gray, whose work I admire, unfortunately provides the perfect statement of social evolution denial in a recent essay:

Social evolution is just a modern myth. No scientific theory exists about how the process is supposed to work. There’s been much empty chatter about memes – units of information or meaning that supposedly compete with one another in society. But there’s no mechanism for the selection of human concepts similar to that which Darwin believed operated among species and which later scientists showed at work among genes. Bad ideas like racism seem to hang around forever, while the silly idea of social evolution has shown an awesome power to mutate and survive.

These claims are very similar to claims he made in a review of Matt Ridley’s book The Rational Optimist over four years ago:

Whatever political goals it is used to promote, the idea of cultural evolution is not much more than a misleading metaphor….Memes are just a pseudo-scientific way of talking about ideas, not actually existing physical entities. There is nothing in society that resembles the natural selection of random genetic mutations; even if such a mechanism existed, there is nothing to say its workings would be benign. Bad ideas do not evolve into better ones. They tend to recur, as racist memes are doing at present in parts of the world where economic dis­location is reviving hatred of minorities and immigrants. Knowledge advances, but in ethics and politics the same old rubbish keeps on piling up. The idea of social evolution is rubbish of this kind, a virulent meme that continues to reproduce and spread despite having been refuted time and time again.

While Gray is correct that cultural evolution does not have human well-being as its goal any more than biological evolution does, he is wrong to deny the existence of cultural evolution, particularly on the grounds that there is “no mechanism” by which cultural evolution can be demonstrated to occur. (See Jason Roy’s interpretation of Gray’s thinking.) It seems that Gray did not, in the four years between the two essays, find time to learn more about cultural evolution, such as by reading the paper Matt Ridley linked in his reply to Gray’s review, Five misunderstandings about cultural evolution by Henrich, Boyd, and Richerson. This (excellent) paper offered by Ridley is a 41-page PDF, written in somewhat technical language; forty-one pages is perhaps asking a lot. But I find it useful to treat cultural evolution as part of my model of reality, and it is discouraging to see such useful concepts discarded without a fair hearing. (Steven Pinker’s take-down of group selection, “The false allure of group selection, probably did not help matters, even though group selection and cultural evolution are not at all the same thing; see also Joseph Henrich’s response to Pinker.) My aim here is to provide an introduction to cultural evolution that is somewhat more respectful of my readers’ time than a 41-page PDF, but also to provide many seductive jumping-off points for further reading.

At the outset, here is an outline of what I mean by cultural evolution:

Humans acquire culture through social learning. There are two major pathways of transmission: vertical, from parents to children only, or horizontal, between unrelated people. The mode of transmission is itself a major selective factor, shaping the content of culture.

Culture cannot survive and reproduce itself without humans; humans, after long dependence on culture, can no longer survive and reproduce themselves without it.

Cultures vary and change, and experience differential “reproductive” success: they spread or fail to spread, and their host populations grow or shrink.

Biological organisms only change by selection on random mutations. Culture, on the other hand, varies in part through intentional (non-random) human action. Despite this, it is rarely the case that humans fully understand all the functions of their culture, or predict how any changes they make will affect them and their descendants. (See, e.g., Alex Mesoudi, Foresight in cultural evolution.)

The relationship between humans and their culture is best modeled as a relationship between host and symbiote or between host and parasite, depending on the fitness cost extracted by culture, with humans as the host.

Humans Eat Culture, Not Food

Culture is not a luxury; it is life or death. Culture has likely been the most important part of the human selective environment for hundreds of thousands of years. Humans are not adapted to life without culture. Robert Boyd, Peter Richerson, and Joseph Henrich (also the authors of the aforementioned 41-page PDF) invite us to consider the “lost European explorer experiment” in order to understand the gravity of our dependence on culture for survival:

[The Lost European Explorer] experiment has been repeated many times when European explorers were stranded in an unfamiliar habitat. Despite desperate efforts and ample learning time, these hardy men and women suffered or died because they lacked crucial information about how to adapt to the habitat. The Franklin Expedition of 1846 illustrates this point. Sir John Franklin, a Fellow of the Royal Society and an experienced Arctic traveler, set out to find the Northwest Passage, and spent two ice-bound winters in the Arctic, the second on King William Island. Everyone eventually perished from starvation and scurvy. The Central Inuit have lived around King William Island for at least 700 years. This area is rich in animal resources. Nonetheless, the British explorers starved because they did not have the necessary local knowledge, and despite being endowed with the same cognitive abilities as the Inuit, and having two years to use these abilities, failed to learn the skills necessary to subsist in this habitat.

Humans rely on culture to survive not only in marginal environments, but even in environments rich with resources, such as the Australian outback. People rely on culture to obtain sources of food, and also to eat their food safely:

In 1860, two intrepid Victorian explorers named Robert Burke and William Wills set out on an expedition to cross the Australian continent from Melbourne in the south to the Gulf of Carpentaria in the north – a distance of 2,000 miles. They were successful in reaching the north coast, but on the return journey they both succumbed to starvation. Burke and Wills were educated modern men, but they did not know how to survive in the Outback. They were living on a plentiful supply of freshwater shellfish and a plant known as ‘nardoo’ that the local Aboriginals ate. However, both contain high levels of an enzyme that destroys vitamin B1, which is a vital amine (hence ‘vitamin’) essential for life. By ignoring the traditional Aboriginal method of roasting the shellfish and wet grinding and then baking the nardoo, which neutralizes the toxic enzyme, Burke and Wills had failed to capitalize on the ancient cultural Aboriginal knowledge. They did not die because of a lack of things to eat, but of beriberi malnutrition. Aborigines did not know about vitamin B1, beriberi or that intense heat destroys enzymes; they just learned from their parents the correct way to prepare these foods as children – no doubt knowledge that was acquired through the trial and error of deceased ancestors. Their cultural learning had provided them with critical knowledge that Burke and Wills lacked. As the two explorers’ fates show, our intelligence and capacity for survival depends on what we learn from others.

Food processing is one of the easiest parts of transmissible, reproducing culture for us to observe. The nixtamalization process, an ancient American method of processing corn, increases the availability of another B vitamin (niacin). Like the shellfish and nardoo of the Outback, corn without its associated cultural processing cannot form the basis of a human diet; where corn traveled without nixtamalization, malnutrition followed.

As Hood notes, above, the people using these cultural food processing methods – and these methods, by the way, are memes – did not need to understand their utility in providing essential vitamins, or even need to understand what a vitamin is. Despite a complete lack of modern chemical knowledge, around the world in vastly different environments with different nutritional challenges, people found diets that supplied all the nutrients they needed in a safe way. And there were many casualties along the way. I wonder if KNM-ER 1808, a female Homo erectus from Kenya who lived 1.6 million years ago and may have died of an overdose of vitamin A, was one of these “deceased ancestors” whose “trial and error” eventually produced cultural solutions. Daphne Miller has posited (in The Jungle Effect) that our sudden switch en masse away from our carefully-evolved recent ancestral diets is behind the most common form of malnutrition in the world today, obesity.

Humans change their culture, but cultures also change humans on the genetic level; cultures themselves formed a major part of our selective environments. Lactase persistence, for instance, seems to have evolved only among dairying populations in Europe, Africa, and the Middle East. The purely cultural availability of milk changed the selective environment, favoring those with the genetic ability to take advantage of this novel source of food.

The Observable Evolution of Artifacts

It’s difficult to visualize the evolution of ephemeral cultural items such as behaviors, rituals, and stories. Focusing on durable artifacts, whose properties may be catalogued and compared, makes this process easer to grasp.

There is one extremely special kind of artifact whose unusual properties make it the perfect introductory example for illustrating the workings of cultural evolution: the chain letter. The chain letter (whether paper or electronic) consists of discrete units of information, almost like DNA, and causes humans to reproduce it. (Most artifacts, like arrowheads and carpets, do not share these properties.) The brilliant Daniel VanArsdale has assembled hundreds of paper chain letters, dating back to the 1880s; his Chain Letter Evolution (which, by the way, is worth spending many leisurely weekend hours immersed in) explains how these documents—literal self-replicators—evolved over the centuries, exploiting beneficial mutations that increased replication:

Apocryphal letters claiming divine origin circulated for centuries in Europe. After 1900, shorter more secular letters appeared that promised good luck if copies were distributed and bad luck if not. Billions of these “luck chain letters” circulated in the last century. As these letters were copied through the decades they accumulated changes from copying errors, offhand comments, and calculated innovations that helped them prevail in the competition with other chain letters. For example, complementary testimonials developed, one exploiting perceived good luck, another exploiting perceived bad luck. Using an archive of over 900 dated letters, predominant types are identified and analyzed for their replicative advantage. In 1935 the first money chain letter appeared, the infamous “Send-a-Dime,” which flooded the world within a few months. The motives and insight of its anonymous author are examined. A 1933 luck chain letter is shown to have provided a model for the Send-a-Dime letter, and this letter itself may have brought unexpected money in the mail to some senders in small towns. In the 1970’s a luck chain letter from Latin America that mentioned a lottery winner invaded the US and was combined on one page with a chain letter already circulating. This combination rapidly dominated circulation. In 1979 the postscript “It Works” was added to it and within a few years the progeny of this single letter had replaced all the millions of similar letters in circulation without this postscript. By examining hundreds of chain letters in the archive, evolutionary hypotheses are formulated that explain these and other events in chain letter history.

Within this small subset of artifacts that are made from information and that cause their own replication (given a population of literate hosts), the tracks of evolution are clearly visible. Most artifacts are not made of discrete units of information, and do not cause their own replication directly; rather, they are the result of intensive social learning of the behaviors required to replicate them. But ordinary artifacts too display the hallmarks of evolution.

In my outline, I mentioned that there are two (basic) pathways of transmission of culture. First, culture may be transmitted from parent to child only; this is vertical transmission (sometimes called phylogenesis). Second, culture may be transmitted between unrelated individuals; for our purposes (and speaking a bit loosely), this is horizontal transmission (sometimes called ethnogenesis). Exclusively vertical transmission results in a perfect, branching “tree-like” cladistic structure; horizontal transmission makes the phylogenetic tree look more like a tangled bush. Another important distinction is the mechanism of memetic transfer: transmission might either be particulate, “all-or-nothing discrete transmission of cultural traits,” or blending, “adopting the average value of a continuous trait from more than one model” (Alex Mesoudi, Cultural Evolution, 2011, p. 57).

The evolution of biological organisms is particulate, in that traits are passed by discrete units of DNA. Biological evolution also mostly relies on vertical transmission, with genes passed from parent to child. However, as Mesoudi notes in Cultural Evolution (p. 100), horizontal gene transfer is common among bacteria and plants, transmitted between unrelated individuals and even across species by viruses. Biological evolution appears to be more of a “tangled bush” than classical models would predict; cultural evolution, however, appears both more particulate and more tree-like than one might expect – that is, more like biological evolution.

In 2002, Tehrani and Collard’s study of Turkmen textiles from the eighteenth century to the present revealed a very tree-like pattern, indicating mostly vertical transmission (“phylogenesis”) and particulate, rather than blending, transmission.

The Turkmen textiles were produced in a context ideal for exclusively vertical transmission, especially prior to 1881: women learned weaving from their mothers, rarely traveled to other villages, and tended to marry within their tribes, reducing the chances for horizontal transmission or “ethnogenesis” to tangle up the phylogenetic tree. Is this result representative of other cultural data sets? Mesoudi, summarizing Branching versus blending in macroscale cultural evolution: A comparative study, by Collard, Shennan, and Tehrani (2006), says:

[I]f biological and cultural evolution really are fundamentally different processes, the former branching and the latter blending…then there should be a systematic difference in the tree-likeness of the biological and the cultural data sets. To test this prediction, Collard et al. collected twenty-one biological data sets that contained genetic, morphological, and behavioral data from a diverse range of taxa, including lizards, birds, hominids, bees, and primates. They also collected twenty-one cultural data sets, including Tehrani and Collard’s Turkmen rug patterns, O’Brien et al’s North American projectile points, other material artifacts such as Neolithic pottery decorations, plus nonmaterial data sets regarding food taboos, religious beliefs, and puberty rites. For each data set, Collard et al. calculated the number of homoplasies [changes due to independent invention or diffusion across lineages or groups], this time using the retention index (RI), which controls for differences in the number of species and characters and is particularly useful when comparing data sets, as was done here….[A]n RI of 1 indicates no homoplasies and a perfectly treelike evolutionary pattern, with lower RI values increasingly less treelike. The results showed that the biological data sets and the cultural data sets had remarkably similar average RIs of 0.61 and 0.59, respectively. Assuming that the biological data sets are primarily generated through branching speciation, this analysis suggests that cultural data sets, too, have been shaped by a similar branching process.

Cultural evolution, then, shares many traits with biological evolution. But, with the exception of the chain letters, what is the substance of memes? How can cultural evolution appear particulate and tree-like if there are no magical particles that code for each cultural trait? An intriguing solution is presented in that same 41-page PDF that no one is ever going to read: attractors. In this model, “it is the attractors that create quasi-discrete representations for selective forces to act on” in the absence of genuine discrete, DNA-like memestuff.

Attractors in Culture Space

Why do cultural data sets reflect evolution as “particulate” as biological evolution, when particulate mechanisms of transmission are extremely rare? Henrich, Boyd, and Richerson argue that the particulate nature is in the traits themselves, rather than the stuff of inheritance:

[C]ultural transmission does not involve the accurate replication of discrete, gene-like entities. Nonetheless, we also believe that models which assume discrete replicators that evolve under the influence of natural- selection-like forces can be useful. In fact, we think such models are useful because of the action of strong cognitive attractors during the social learning.

The reason is simple: cognitive attractors will rapidly concentrate the cultural variation in a population. Instead of a continuum of cultural variants, most people will hold a representation near an attractor. If there is only one attractor, it will dominate. However, if, as seems likely in most cases, attactors are many, other selective forces will then act to increase the frequency of people holding a representation near one attractor over others. Under such conditions, even weak selective forces (“weak” relative to the strength of the attractors) can determine the final distribution of representations in the population.

Attractors are forms that frequently appear to be the targets of convergence; they are indications of strong constraints in the spaces in which they appear. Donald E. Brown’s list of human universals (from his excellent 1991 book, Human Universals) provides a list of likely “attractors” in human space – products of cognitive, physical, and social constraints. When a feature is common to all human societies ever studied, such convergence is a strong indication of the presence of constraints. The human poetic line tends to be just around three seconds long – about the length of a human breath. The pentatonic scale is found all over the world and is encoded in 40,000-year-old flutes found in European caves made from the bones of vultures.

Human universals are far from a comprehensive list of attractors. Many stable attractors exist only at a very complex level of development that not all human groups have attained, for instance. But the particulate nature of the space of possible cultural solutions can explain the particulate nature of cultural evolution even in the absence of particulate “meme DNA.”

The Cultural Evolution of Massive Institutions

It is easy to see the processes of cultural evolution in the small scale, in projectile points, language, and carpets; but evolutionary processes are also visible in the macroscale. Peter Turchin has proposed that the unprecedented mega-empires beginning around 3000 B.C. were the products of cultural evolutionary constraints. A theory for formation of large empires presents a model in which large empires are constrained into existence by warfare and competition between nomadic herders and settled agrarian societies; as with agriculture crowding out hunting and gathering as a viable way of life, smaller-scale societies simply could not exist. It is not safety that created these giant engines of “cooperation,” but danger and necessity. He says:

Nomads are hard to tax, because they are skilled at fighting and can move themselves and their wealth much more easily than farmers can. Moreover, their chief product—livestock—cannot be stored easily, unlike the grain produced by agrarian economies. Thus, political organizations among nomads had to draw resources from the agrarian societies, by robbing the farmers, by extorting tribute from agrarian states, or by controlling trade routes….This argument suggests a reason why the sizes of agrarian states and nomadic confederations are correlated. As agrarian states in East Asia grew, nomads needed to cooperate on an increased scale to continue successful raiding, to present a credible threat to extort the tribute, or to impose favourable terms of trade. Additionally, larger and richer sedentary states possessed greater wealth that nomads could extract, thus enabling larger nomadic polities. Consequently, Barfield calls the nomadic confederations the ‘shadow empires’, their size mirroring that of agrarian states.

Thus, Barfield and Kradin suggest that the appearance of agrarian mega-empires explains the rise of nomadic imperial confederations. This is probably correct. However, if the presence of a large agrarian state produced larger nomadic confederations, should not the presence of a large nomadic confederation have similar effects on farmer societies?

The evolution of religion is one of the most interesting and ignored areas of cultural evolution. We tend to exaggerate the degree of rationality and conscious thought in human life, ignoring the enormous and influential contribution of magical thinking. Just as there are vital amines (vitamins) that human cultures must figure out how to supply us with, there are social and cognitive equivalents; modernity may do as poor a job supplying us with social belonging and ritual as it does supplying us with proper nutrition.

How Transmission Pathways Matter

In my outline, I mentioned that the transmission pathway – vertical or horizontal – matters a great deal for the content and friendliness of transmitted cultural items.

In biology, there is already support for this model. Parasitic entities like bacteria that are limited to vertical transmission – transmission from parent to child only – quickly evolve into benign symbiosis with the host, because their own fitness is dependent on the fitness of the host entity. But parasitic entities that may accomplish horizontal transmission are not so constrained, and may be much more virulent, extracting high fitness costs from the host. (See, e.g., An empirical study of the evolution of virulence under both horizontal and vertical transmission, by Stewart, Logsdon, and Kelley, 2005, for experimental evidence involving corn and a corn pathogen.)

As indicated in an earlier section, ancient cultural data is very tree-like, indicating that the role of horizontal transmission has been minimal. However, the memetic technologies of modernity – from book printing to the internet – increased the role of horizontal transmission. I have previously written that the modern limited fertility pattern was likely transmitted horizontally, through Western-style education and status competition by limiting fertility (in The history of fertility transitions and the new memeplex, Sarah Perry, 2014). The transmission of this new “memeplex” was only sustainable by horizontal transmission; while it increases the individual well-being of “infected carriers,” it certainly decreases their evolutionary fitness.

Parent-child transmission plays an increasingly limited role in cultural evolution. Horizontal transmission allows for the spread of cultural items that are very harmful to the fitness of host organisms, though they may (or may not) benefit the host organism in the hedonic sense. Indeed, the carefully evolved packages of culture transmitted for hundreds of thousands of years from parents to children are almost certainly too simple to solve the complex problems that moderns face.

Unselfconscious evolution is no longer up to the challenges of the fast changes of culture. As my hero Christopher Alexander says in Notes on the Synthesis of Form,

[T]he culture that once was slow-moving, and allowed ample time for adaptation, now changes so rapidly that adaptation cannot keep up with it. No sooner is adjustment of one kind begun than the culture takes a further turn and forces the adjustment in a new direction. No adjustment is ever finished. And the essential condition on the process—that it should in fact have time to reach its equilibrium—is violated.

While unselfconscious evolution with limited foresight can no longer be relied upon to produce solutions of good fit, an understanding of evolutionary processes is essential to producing such fit. In particular, the constraints that have not changed for humans – nutritional, social, and cognitive – must be recognized, and old, hard-won solutions to these constraints must be seriously considered as essential building blocks of synthetic, selfconsciously-designed solutions to human flourishing.

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47 thoughts on “Why Cultural Evolution Is Real (And What It Is)”

Gray raised a question that I don’t think you directly answered: “there’s no mechanism for the selection of human concepts similar to that […] at work among genes”. To my understanding, it’s the selective pressures that make an evolutionary process and without these pressures there’s only random drift. Culture seems more prone to random drift than any directed refinement.

You’ve raised two examples of cultural processes subject to selective pressure but they fall more into the category of material technology than social mechanism. Food can give very clear feedback if improper preparation or lack of a particular nutrient result in death. Rudders can be compared to other rudders along very simple design criteria – do they result in less labor intensive, easier to control ships. Are there similar pressures on religious customs or are these subject to a fundamentally different process?

These are harder to study in that they don’t leave study-able artifacts – but note that many of the cultural data sets analyzed by Collard, Shennan & Tehrani were of just this sort (food taboos, religious beliefs, puberty rites). My point here is to establish the reality of cultural evolution; if the cultural processes that leave material artifacts evolve, the burden of proving that non-material culture also evolves seems to shift somewhat.

I think it’s likely that religious beliefs and rituals (and remember here that diets are often religious matters – just ask a vegan friend!) DO produce immediate feedback in the form of happiness and cooperation, or misery and chaos – Alexander’s “misfit” – just like material culture. (Tracing the LOSS of religious ritual in our time demonstrates this.) My next project is about varieties of consciousness and how social practices like rhythmic ritual sustain them.

The Seventh Day Adventists, Jains, some sects of Buddhism, Sikhism and Hinduism have vegetarianism as tenets of their religions, but I’ve yet to hear of a religion that has veganism as one of its tenets. Which religion is that?

I admit a certain amount of my initial skepticism originated from not seeing how cultures themselves fit into the heritable structure. Entire cultures don’t reproduce into multiple child cultures with slightly modified selections of traits which then compete. It requires the meme model to produce something of this sort, in which each person represents a kind of parallel sub-culture of the dominant culture in their region.

Evolution requires a heritable structure, an abundant population of entities to compete, and a constraining fitness function that prunes entities that don’t measure high on it’s scale. Rudders match this very well. They don’t naturally reproduce but a craftsman that makes a new rudder will generally match the design of some old rudder with minor imperfections or slight tweaks. Ever boat rudder competes with the others in a given community and there’s no scarcity of rudders. It’s easy to tell which rudders are superior to others and one that performs worse than its neighbors will not be selected to pass on its design. Makes for a good example and I agree that the pattern generalizes well to other technologies.

The English attitude for tea is also a cultural construct. Does it fit the same pattern? We could take everyone who takes tea to be the population of entities and consider the heritable structure to be horizontal transfer when someone is culturally socialized into observing tea time. It’s not clear what the fitness function is here.

The American attitude for using precise timing in their schedules is another cultural construct. Again we can take the meme pattern for population and heritability structure but it’s still not clear to me the fitness function at play.

Constraining the accepted definition to translation to a small subset of tasks that can be labelled ‘literal translation’ is a historic artifact of the outsize importance the Bible held in Christian society and the belief in it’s immutable message. There’s a greater variety of translation styles that are dismissed as ‘interpretations’ or ‘adaptations’; I don’t see that this must be inevitably so. If you can convince me that these other types of cultural entities fit into an evolutionary model that would go far in convincing me.

“Gray raised a question that I don’t think you directly answered: “there’s no mechanism for the selection of human concepts similar to that […] at work among genes”. To my understanding, it’s the selective pressures that make an evolutionary process and without these pressures there’s only random drift. Culture seems more prone to random drift than any directed refinement.”

Philosopher of science David Hull uses the phrase “variation and differential perpetuation” to portray the algorithm of evolution. The key is that if some patterns are preserved better over time (are not deselected), spread faster, or are replicated at a greater rate, then the population will change dramatically over time. Add in a bit of variation due to copying errors, intentional variation, recombination, or the introduction of novel patterns and you have an evolutionary process. Full stop.

What causes some patterns to be preserved, spread or replicated faster? Lots of things, all extensively elaborated by Boyd, Richerson, Henrich, Dennett and Mesoudi among others. People face common problems and selectively copy those they are exposed to. Parents are concerned about their kids and teach them things they think will be useful. Some things are easier to remember or more obvious than others. Some things Integrate in well with the existing population of ideas and others lack the support of other ideas and patterns. Some things are easy to replicate, others are extremely hard to. Some variations fail to solve the problem and others do so nicely.

Cultural evolution is much faster and more complex than genetic evolution and in a sense, Gray is right that the selection mechanisms are not necessarily similar. But they don’t need to be similar.

Assuming we’re standing in front of a time series of data showing some change in patterns over time, I want to be able to distinguish evolution from something different and then have that difference matter. Say our distinguishing feature is that some patterns in the time series replicate and spread faster over time. A mountain eroding over centuries has a change in pattern but no replication so no evolution. Over the course of a few hours, fire can be wildly successful at replicating but evolutionary process doesn’t feel like it ought to apply to forest fires. So I’m going to slightly change your point to emphasize and require the presence of copying errors and recombination (fire having no variation between ‘generations’). No arguments that humans learn through mimicry so there’s definitely an element of faulty copying in cultural behavior.

Is ritualized tea drinking evolution then? Now it’s no longer disingenuous to say “well, it was not de-selected so it must have been implicitly selected” as we’ve discarded any mention of selection. Tea rituals require human learning which requires faulty copying and the question is answered. Is that all? If we can just find an element of replication in law generation then we’re allowed to apply any theoretical evolutionary results to the process. The same with small business power dynamics. Or small town layout across countries. Or choosing to run marathons. Or farmer arguments over water rights. Or public places displaying statues restricted to a muted range of emotions. Not all of these feel like evolution to me. At this point, I suspect my discontent comes from missing something important so feel free to ignore this and any subsequent comments as novice noise about definitions.

I would say law clearly evolves over time, and that common law is (in hind sight) structured to evolve. The institutions of law and the procedures for changing laws evolve too.

As for small business power dynamics, I would just suggest that that the dominant forms of organization and institutions and the values, beliefs and norms have evolved. The very existence of a small business (private partnership or incorporation) is an evolved organization which provides the backdrop for power dynamics (which also exist in other primates or other historical eras with totally different rules and dynamics) Is the appropriate response to a status insult a challenge to a duel or forming an opposing peaceful political coalition?

I would say the small town layout and population evolves over time. Millions of people making decisions on where to live which affects other decisions. As technology and transportation and other institutions evolve, so do the incentives and freedoms to live one place or another.

I wouldn’t suggest choosing to run a marathon is framed well as an aspect of cultural evolution. I would suggest that the existence of institutional races of a particular length with particular rules and particular sites and their overall popularity can be modeled as evolution. These of course influence both the possibility and likelihood of the choice.

Same with arguments over water rights. The institution of property rights has itself evolved, as have accepted norms on how to structure the fight (rock to back of head, or take it to the local lord, or sue in court?)

On statues, power dynamics and arguing over water, I think you are hitting on the fact that our biology constrains our choices and strongly influences cultural evolution. I would of course agree.

One thing to keep in mind is that the lack of predictive power of a theory of cultural evolution isn’t a fatal problem. After all, our theory of biological evolution doesn’t do much good at predicting what will evolve next.

Perhaps an epidemiological framework is helpful for thinking about memes?

Interesting essay, I found it particularly curious to see a theory of cultural evolution detached from a necessary normative political programme following it or guiding it. The master’s thesis I finished at college back in November touched on similar subject, to be specific ideas of cultural progress as guiding the creative process in the arts. I wonder how much the concept’s reputation has been damaged by its association with either classical liberal “Whig history”, Hegelian-Marxist historiography or Spenglerian pessimist conservatism and that’s why so many people are skeptical about accepting it.

transientpetersen made a good observation that leads into my thoughts:

Gray raised a question that I don’t think you directly answered: “there’s no mechanism for the selection of human concepts similar to that […] at work among genes”. To my understanding, it’s the selective pressures that make an evolutionary process and without these pressures there’s only random drift. Culture seems more prone to random drift than any directed refinement.

Indeed. If culture “evolves,” what are its units (like DNA for biological traits)? What exerts selective pressure? What decides fitness?

It just doesn’t quite work.

Fundamentally I think the key error in this view of the matter is thinking that culture and its evolution are something divorced from biological evolution. They are not. Indeed, rather culture and cultural evolution are largely (but perhaps not entirely) facets of biological evolution, encapsulated by hbd* chick’s perennial question, “where does culture come from?”

That question, by the way, was also not answered in this piece.

Because culture contains elements that are not fully captured by biological evolution (that is, aspects of culture change far faster than biological evolution alone would permit), there may be limited justification for thinking of it as a somewhat separate entity. But, one can do so as long as one keeps in mind this fact: culture is fully constrained by biological evolution. Biology constrains which “memes” (I dislike that term, for the record) survive and which fail. Plain physics offers a bound, as your example of the rudder illustrates, but what also determines which memes are successful and which fail is the innate temperaments of the individuals which embrace them.

Examining culture and its evolution as entities to themselves has the most utility in explaining changes of cultural fashions that occur faster than natural selection would permit. Clearly, something is acting over and above evolutionary change, even if that something is bounded by evolution.

I have largely taken the simplified view that “culture” is mainly the result of the interaction of innate tendencies and the social-economic-technological landscape of the day – in short, the incentive structure. Modern societies present rewards and costs/punishments for pretty much everything. Individuals, with more or less “fixed” temperaments, are going to vary their behavior according to incentives available. Different individuals with different temperaments are going to respond to the same set of incentives in different ways, giving you variation across space, and the changing incentives – driven by technology and the behavior of other individuals in the society – leads to changes across time.

In this way, success of a given “meme” depends on temperaments of individuals in question and the current reward structure.

So it was biological evolution that caused the chain letters to evolve, aye?

When I think of concrete examples of cultural evolution my mind turns to military technology and tactics. One can argue that the type of military one fields and the type of cohesion your army has reflects genetic dispositions. This is undoubtedly true. But if your argument stops here and moves no further then you have painfully limited your ability to understand the way military organizations–and really, all social organizations–actually work.

Security studies folks are obsessed with this topic (though they don’t use the word ‘cultural evolution’ — preferred terms include “generations of warfare” and “revolution in military affairs”). It isn’t hard to see why. The selection mechanism for cultural evolution in the military realm is cold and brutal: death. Those who do not adapt on the battlefield die on the battlefield. If the enemy is fighting in a way superior to your own you must change to fight as they do — or find some way to fight better. Those who don’t are defeated.

There is a story often told about armies in the ancient west, progressing from chariots and champions to massed phalanx formations to more flexible maniples to Marian legions and so on to the future. A parallel–but less commonly related–tale would speak of chariot and champions of ancient China, replaced by armies of massed spear men and crossbowmen, who in turn were replaced by great mobile cavalry columns whose tactics, weapons, and dress mirrored the nomadic hoards they fought. The modern age has its own version: troops line up in neat formation, firing in volleys, soon they would rush around in great masses, occupying what the artillery laid bare, then they would not rush at all, hiding behind embankments and in ditches, creating zones of fire where no living thing could cross. Then came the Blitzkreig and maneuver warfare. That model is what most armed forces in world stick with today.

It is worth thinking about how this came about. Political scientists and military theorists have developed some fairly sophisticatedmodelsandexplanations for how new military doctrines, tactics, and systems develop, but for our discussion the more interesting question is how they spread. Blitzkreig-style maneuver warfare is as good as an example as we’ll get. In 1939 There was one power doing it. By the end of the war everybody with tanks was doing it. The model has stuck – in the American invasion of Iraq can be heard the echoes of German tanks rushing across France.

When we are talking war it is easy to see what “exerts selective pressure” and “decides fitness.” But it is not hard to the similar (if less deadly) processes at work elsewhere. The reason pop songs from New Delhi, Tokyo, New York, and Moscow all have the same structure, that scientists researching in India, Japan, the U.S., and Russia all use the same methods, and that the military academies in all four places teach similar doctrines are the same. Ideas and practices die out much faster than people do.

So it was biological evolution that caused the chain letters to evolve, aye?

To ask that question seems to convey general misunderstanding of my points.

The answer is both yes and no. Yes in that “culture” is bounded by biology. The origination and success of a “meme” is strictly limited by biological factors (the creator needs to conceive it; other people have to embrace it). That is not the same as saying that culture adds nothing beyond biological evolution, for it does. Can you see how those both can be the case? So the answer is no in the sense that biological evolutionary forces (i.e., genetic change) are not all that are involved.

When we are talking war it is easy to see what “exerts selective pressure” and “decides fitness.”

That too involves a degree of biological evolution – in the form of the (valid version) of group selection where the victors exterminate and replace the losers – or at least impose their way of life (and genes) upon the vanquished.

But, as I noted above, plain old physics is also a constraint on the evolution of “memes,” as beautifully exemplified by military tactics. Unfortunately, plain physics alone (well, in the sense of not going down to the level of biology and psychology, since everything is physics) is not enough the explain the success or failure of most memes, since a good share aren’t necessarily optimal ways to solve some problem or accomplish some task. That is, unless you invoke evolutionary effects, which brings us back to biology. But as per the above, the overall incentive structure must also play a role, since biological evolution is insufficient to explain rapid changes.

So to sum up, “cultural evolution” depends on/is driven by:

*Biological evolution
*(Extrabiological) physics (which includes technology, geography, etc.)
*The social landscape (i.e., what other people are doing).

That’s the overarching process. What should follow now is filling in the details.

“If culture “evolves,” what are its units (like DNA for biological traits)? What exerts selective pressure? What decides fitness?”

Darwin did not know what units were being transmitted when he detailed his theory of biological evolution. So I am not too worried about the first. But as a place holder let’s call these units ideas. We will call the mechanism through which they spread learning.

What exerts selective pressure is human competition. What decides fitness depends on the idea in question — for a pop melody it is being “catchy.” For a business plan is it profit. For a military doctrine it is success on the battlefield.

What exerts selective pressure is human competition. What decides fitness depends on the idea in question — for a pop melody it is being “catchy.” For a business plan is it profit. For a military doctrine it is success on the battlefield.

Yeah, that doesn’t quite work. For one, not all “memes” are “functional”, at least not in the short run. They don’t serve to achieve some immediate end, like say a business plan or a military tactic. Most of religion, ideology, and fashion falls under that umbrella. What determines the success of these types of memes?

Furthermore, you haven’t actually solved any problem with this idea, merely transported the problem somewhere else. Why are some tunes “catchy?” Why are some fashion trends hip? Why do the latest diet fads stick? Why do different baby names or parenting practices come into and out of favor? In short, we’re back to HBD Chick’s question: where does culture come from?

Thinking of cultural aspects as subject to their own form of evolution seems work primarily as far as they are driven by actual biological evolution. Biological evolution is the equivalent of the g factor to cultural evolution, it would seem.

To the extent that culture changes beyond mere biological change, we still don’t know how or why. Technological bounds are surely one reason. But the incentive structure afforded by technology and the social environment (i.e., the current collective behavior of everyone else) seem to be involved.

It’s my own suspicion that technology and current social factors act in a dynamic fashion to drive cultural change. These changes are still sharply bounded by biology, but social behaviors can serve to create feedback loops that stir change. Fashion, for example, appears to be driven by what high-status individuals are doing. With these dynamics playing out, we can see a churn of cultural changes, given the fairly wide space of possibilities today.

The model you seem to be using is this: genetics -> “personality” -> culture. (with environmental arrows and payoffs thrown in). (BTW, you might find Ruth Benedict’s book Patterns of Culture to be a fun read. It is old-fashioned anthro and uninformed by genetics or evolution, but the basic idea is that human cultures can be represented by personality types. See: http://en.wikipedia.org/wiki/Ruth_Benedict#Work)

I always go back to the diversity of human language. You would be hard pressed to argue that the French speak French and the English speak English because of genetic responses to differing physical environments, or because the French personality type (?) naturally makes them want to speak a romantic language. English babies raised in France speak French, after all. Whatever effects external environment have on linguistic evolution, they were apparently not strong enough to induce European Americans to start speaking Native American languages upon colonization.

A better model, I reckon, is that individuals imitate the language of others as they develop; proper grammar and pronunciation is reinforced by parents, etc. Slight individual-level changes in speaking style (probably influenced by genetic variation) provide variation, the distribution of which will likely change across generations, if only by random “drift” (just listen to how folks talk in old movies!). Or perhaps the speaking styles of higher class folks are more often copied by others, inducing a sort of selective pressure? Whether you want to call these dynamics “evolutionary” or not is entirely a semantic issue: who cares? But I think the evidence suggests that some cultural systems can have some autonomy from genetic and environmental constraints, at least on historical timescales.

Forgive me if I have straw-manned you here. You did mention that culture as an autonomous system can be useful in investigating the changes in trends through time, which is similar to my “historical timescale” claim above.

I certainly agree that biology constrains culture. Not sure anyone would disagree. I don’t think We should be redefining culture into a synonym for institutions though(which are a subset — or type — of culture along with ideas, tools, and techniques).

On your question of what are the units of selection I think it is useful to focus on the phenotype not the genotype (or memotype). Unlike biology which uses a common coding system for various phenotypic effects (on behavior or structure), culture does not share this convenient coding structure. There is an infinite potential number of ways to code for a given behavior and there should be no assumption that we code “how to tie our shoes” the same way in each of our brains (nor even that the only way to code for it is in a brain).

What selects? Survival and replication/amplification of the cultural variation. As Boyd, Richerson and Henrich have delineated this can be because an idea is easier to remember, more obvious, easier to explain, easier to test, more likely to work, more likely to lead to more or less copies of itself, fitting into a larger complex of ideas (shoe wearing as opposed to sandal wearing), less likely to cause the relative failure of the idea holder, etc etc.

Cultural evolution is very different from biological evolution. And yes they constrain and influence each other. But if properly adapted to the differences and distinctions, the application of the concept of evolution is essential to understand cultural change.

It’s a bit odd that you start off with writing about how well-educated European explorers were unable to find sufficient food, because of a lack of cultural background, and then wind up concluding that “Unselfconscious evolution is no longer up to the challenges of the fast changes of culture. …” and recommend we consider “selfconsciously-designed solutions to human flourishing”.

But what makes you think that self-consciously designed solutions to human flourishing are doable? Frederick Hayek won a Noble prize in economics for observing that the main function of an economy is to make use of dispersed knowledge about local conditions that no single person can hold.

You’re right to be suspicious of it and Hayek is a genius. I’m taking Chris Alexander’s Notes on the Synthesis of Form as a starting point – looking at how old cultures adapted to change, realizing that’s no longer possible, figuring out where to go from there. I am not proposing unilateral or top-down change that ignores networks and economics; we should start much smaller, with e.g. architecture and ritual.

Thank you for this blogpost. It gives an excellent introduction into the scientific research behind the (too?) much popularized concept of cultural evolution, accessible for newcomers to the field, while avoiding (over)simplifications. Writing a PhD in systematic theology on evolutionary studies of religion (http://www.kuleuven.be/research/researchdatabase/project/3H12/3H120419.htm), I know how hard it is to write such an introduction… Fortunately, I noticed I already read quite a few of the sources you linked to, so I guess I’m on the right track in that regard 😉 I would like to reblog this, if that’s OK for you: this would be an excellent read for my colleagues, especially for those who do not (yet) consider cultural evolution relevant for theology!
Much of the reluctant attitude towards cultural evolution in theology stems, in my opinion, from the idea, fueled by popular presentations of the field by e.g. D. Dennett, or R. Dawkins, that cultural evolution reduces religion to ‘nothing but’ unconscious processes of natural selection. I think the conclusion of your essay could help to foster a more constructive attitude of theologians towards evolutionary studies of religion, since there you put forward the idea of ‘self-conscious evolution’. Of course, I’m not claiming that natural sciences should accommodate theology (as part of humanities), or vice versa, but I do think that a certain consilience between evolutionary approaches of culture/religion, and other approaches, including theology would be fruitful. I know, that raises questions on the relation between theology and natural sciences that go beyond the focus of your essay, so I won’t further expand upon that.
Suffice it to repeat that I appreciate this post, for the fact that it brings together a bunch of good source material, for the clear exposition of a complex field, and – this is my academic self-interest rearing it’s intellectual head – the possible connections with my own research (although I obviously would love to read more than just one paragraph on your thoughts on the evolution of religion)!

“Much of the reluctant attitude towards cultural evolution in theology stems, in my opinion, from the idea, fueled by popular presentations of the field by e.g. D. Dennett, or R. Dawkins, that cultural evolution reduces religion to ‘nothing but’ unconscious processes of natural selection.”

I agree. It is like explaining away heart surgery as nothing but an unconscious evolutionary process. I think their (popularized) depiction of religion is less than productive to put it mildly.

Religion, like most cultural institutions, solves problems and serves purposes — much like courts of law, property rights, heart surgery, or the consumption of french fries.

Religions serve lots of purposes some which are clearly conducive to general welfare, some to special interest groups (the clergy or elites?), and some may just be emergent features which serve nobody in particular and may even result in negative overall effects to humanity.

Cultural institutions are built up and dependent upon shared values and beliefs (Douglas North). Obviously religions are excellent institutions to spread and propagate shared beliefs and values. As such, my assumption is that they are probably ultra critical to social welfare and outcomes (both positively and negatively).

Nicholas Carr just posted a short except from his new book focusing on evolution as a model for technological progress [http://www.roughtype.com/?p=5372]. As additional reinforcement to his point, I’d add the continued success of the qwerty keyboard.